The present invention relates to an electromechanical driving device for use in a tailgate of a motor vehicle.
European patent EP 0 937 187 B1 discloses an electromechanical driving device of the generic type. The device is intended for use in a tailgate of a motor vehicle and comprises an electric motor for driving in rotation a spur gear which is accommodated in a transmission housing and which is operatively connected to a transmission arrangement in order to drive an output shaft for a windshield wiping device. In addition, the electromechanical driving device is mechanically connected to a closing device for closing the tailgate, wherein the device itself is embodied as a driving device for a rear windshield wiping device, and the electric motor serves as an electric drive for actuating the wiping device by means of a transmission arrangement. In order to actuate the closing device and in order to drive the wiping device, the electromechanical driving device is of modular design, wherein the electric motor can be actuated in both rotational directions, and in one rotational direction the transmission actuates the force transmitting train to the wiping device, and in the other rotational direction it actuates the force transmitting train to the closing device. In this way, the wiping device or the closing device can optionally be actuated as a function of the rotational direction of the electric motor.
In such a driving device, a freewheel is necessary so that when the wiping device is actuated the force transmitting train to the closing device is interrupted, while, on the other hand, the force transmitting train to the wiping device has to be interrupted if the closing device is to be actuated. According to the known embodiments, drivers are provided in the spur gear of the driving device for this which interact with an actuating lever, and the interaction starts or fails to occur depending on the rotational direction. The actuating lever must, in this context, be connected here in a structurally complicated way by means of a cable pull to a connecting member which brings about a necessary rotation in the closing device which is analogous to that of the door key in the tailgate. According to the embodiment in the prior art, a specially configured transmission housing is also necessary, which transmission housing accommodates the actuating lever and the cable pull which is embodied as a Bowden cable, and in addition connects the closing device to the driving device in order itself to provide the modular design of the driving device with the closing device.
This results in the object of the present invention of providing an electromechanical driving device for use in a tailgate of a motor vehicle which has a simple design for generating optional actuation of a windshield wiping device or of a closing device and comprises a transmission housing which is embodied according to a known design for driving a windshield wiping device.
The invention includes the technical teaching that a shaft section of the spur gear shaft extends out of the transmission housing on which means for actuating a closing device for closing the tailgate and/or a tailgate windshield are accommodated.
The invention proceeds from the idea, on the basis of a driving device having a transmission housing of a known design, of merely modifying the length of the spur gear shaft for the sake of simplification, with the result that a shaft section extends out of the transmission housing in order to provide the possibility of accommodating the means for actuating the closing device for closing the tailgate and/or a tailgate windshield. The closing device can be designed both to close the tailgate, such as are known, for example, in station wagons, compact vehicles or compact cars, wherein depending on the way in which the tailgate is embodied the tailgate windshield itself can be made such that it can be opened or closed.
The spur gear shaft is connected to the spur gear in a rotationally fixed fashion, with the result that the rotational movement of the spur gear is transmitted to the spur gear shaft, and the shaft section, extending out of the transmission housing, of the spur gear shaft also co-rotates.
According to one advantageous embodiment of the means for actuating the closing device, said means comprise a freewheeling device which causes the closing device to be actuated when the spur gear shaft rotates in a first rotational direction, and causes freewheeling of the spur gear shaft in an opposite second rotational direction. Depending on the rotational direction of the electric motor, the spur gear shaft can either execute right-handed rotation or left-handed rotation, which is described by the first rotational direction or the opposite second rotational direction. The freewheeling device is part of the force transmitting train between the driving device and the closing device here.
According to one advantageous embodiment of the freewheeling device, said device has an actuating lever which is accommodated in a co-rotating fashion on the shaft section of the spur gear shaft and is operatively connected to a closing device lever which is embodied in a wedge shape in the rotating direction of the actuating lever. The actuating lever can be pressed onto the shaft section or connected to it in some other rotationally fixed fashion. If the spur gear shaft rotates, the actuating lever also rotates in a rotational plane. A closing device lever extends into the rotational plane from the closing device, wherein the closing device lever is of wedge-shaped design. If the actuating lever rotates as a result of the rotation of the spur gear, the actuating lever can run up against the wedge-shaped closing device lever in order to close the force transmitting train between the driving device and the closing device.
The actuating lever is advantageously of elastically sprung design in the direction of extent of the spur gear shaft, with the result that said actuating lever runs up against the wedge-shaped closing device lever in a positively locking fashion in order to actuate the closing device in the first rotational direction, and in the second rotational direction it slides away in a sprung fashion over the wedge-shaped closing device lever in order to bring about the freewheeling of the spur gear shaft. The wedge-shaped configuration of the closing device lever relates to a wedge-shaped cross section, with the direction of the wedge being in the rotational plane of the actuating lever. If the actuating lever rotates in the first rotational direction, it can also run up at least on the end side against the blunt side of the wedge cross section of the closing device lever in order to transmit the actuating force to the closing device in a positively locking fashion. If the actuating lever rotates in the second rotational direction, the actuating lever slides away over the closing device lever since the latter does not bring about any positive locking with the closing device lever on the running-up side of the wedge cross section. A freewheeling device is therefore provided, and in this context, for the purpose of reliable actuation of the closing device, at least one full rotation of the spur gear is necessary to ensure that the actuating lever runs up against the blunt side of the wedge-shaped cross-sectional profile of the closing device lever. According to one further advantageous embodiment of the freewheeling device there is provision for the latter to be embodied in the form of a sleeve freewheel which is arranged on the shaft section of the spur gear shaft and on which the actuating lever is accommodated.
A sleeve freewheel comprises two sleeve sections which are placed concentrically one in the other and between which clamping bodies are introduced with the result that the outer sleeve can be rotated with respect to the inner sleeve in only one rotational direction and is blocked in the other rotational direction. The sleeve freewheel is pressed with the inner sleeve onto the shaft section of the spur gear shaft, with the actuating lever being connected to the outer sleeve of the sleeve freewheel. If the shaft section of the spur gear shaft rotates in the first rotational direction, the rotational movement is transmitted from the inner sleeve to the outer sleeve of the sleeve freewheel and the actuating lever can co-rotate. If, on the other hand, the shaft section of the spur gear shaft rotates in the second rotational direction, the rotational movement is not transmitted from the inner sleeve of the sleeve freewheel to the outer sleeve, and the actuating lever is not made to rotate.
A spring element is advantageously arranged between the actuating lever and the transmission housing in order to prevent undesired rotating back of the actuating lever in the second rotational direction. This enables a defined position of the actuating lever to be ensured, in which case the spring element can be embodied, for example, in the form of a small leaf spring. The leaf spring can come to bear laterally against the actuating lever, with the result that the actuating lever is positioned only a few angular degrees before locking with the closing device lever.
A further advantageous embodiment provides that a second freewheeling device is arranged between the spur gear and the transmission arrangement, which freewheeling device interrupts the transmitting of movement to the transmission arrangement when the spur gear rotates in the first rotational direction, and in the opposite second rotational direction it causes the movement to be transmitted. The first freewheeling device brings about a rotational-direction-dependent interruption of the force transmitting train in the direction of the closing device, while the second freewheeling device brings about a rotational-direction-dependent interruption of the force transmitting train in the direction of the transmission arrangement.
The second freewheeling device advantageously comprises a guide groove which is provided in a planar fashion in the spur gear and has a ramp-shaped raised portion, wherein a spring-loaded bolt, which is connected to the transmission arrangement, is guided in the guide groove. The ramp-shaped raised portion is bounded by a run-up side and by a stop side, and during a rotation of the spur gear the bolt slides away over the run-up side in the first rotational direction, and in the case of a rotation in the second rotational direction it runs up against the stop side in a positively locking fashion, with the result that the movement can be transmitted to the transmission arrangement. The ramp-shaped raised portion is provided on the bottom in the guide groove and one, two or four thereof can be provided on the full circle of the guide groove within the planar side of the spur gear. It is therefore no longer possible to achieve the positively locking transmission of force via the stop side only at a maximum rotational angle of 360° but now it can even be achieved at 180°, 120°, etc. A helical spring applies force to the bolt and presses it against the base face of the guide groove. If the spur gear runs in the first rotational direction, the bolt slides away over the bottom side of the guide groove and when the ramp is reached it slides up onto the ramp over its oblique side and when the end of the ramp is reached it clicks back into the bottom face of the guide groove through the application of spring force. It is therefore possible to dispense with transmission of the rotational movement of the spur gear to the transmission arrangement. However, if the spur gear rotates in the direction of the second rotational movement, the ramp runs up with the stop side against the bolt, with the result that the rotational movement can be transmitted to the transmission arrangement.
According to a further embodiment of the second freewheeling device, the guide groove which is provided in a planar fashion in the spur gear is embodied with a locking spring, wherein when the spur gear rotates in the first rotational direction, the bolt which is guided in the guide groove slides away over the locking spring, and in the case of rotation in the opposite second rotational direction it runs up in a positively locking fashion against the locking spring, with the result that the movement can be transmitted to the transmission arrangement. The compression spring which is arranged on the rear of the bolt, for pressing the bolt against the guide path, is therefore dispensed with since the locking spring provides the resilience in order to slide away under the bolt and run up against the bolt in a positively locking fashion in the second rotational direction. The locking spring can, however, also be embodied as a spring-loaded locking element which projects out of the guide path in a catch-like fashion, and it can be pressed down through the bolt when it runs over the bolt in the freewheeling direction and forms a stop side in the locking direction in order to close the force transmitting train of the spur gear to the transmission arrangement.
As has already been described in the embodiment of the first freewheeling device, it is advantageously possible for the second freewheeling device also to be embodied in the form of a sleeve freewheel which is arranged on the spur gear shaft and on which a transmission lever, which is operatively connected to the transmission arrangement, is arranged. The spur gear shaft can specifically also have a prolonged section in the opposite direction to the shaft section, which prolonged section extends into the transmission housing. The sleeve freewheel can be pressed onto this shaft section in the form already described above and can bring about the freewheeling in the first rotational direction in a known method of functioning, and in the second rotational direction it can transmit the rotational transmission of the inner sleeve to the outer sleeve of the sleeve freewheel and therefore drive the transmission arrangement. The transmission arrangement can be embodied, for example, as a conversion gear mechanism, in which case a four-bar mechanism arrangement also constitutes a possible embodiment. In transmission arrangements of the known embodiments, the spur gear firstly comprises an eccentric transmission bolt to which a transfer lever is arranged in an articulated fashion. According to the present embodiment, the eccentric arrangement of the transmission bolt is implemented by means of a transmission lever which is connected in an articulated fashion to the conversion element. The transmission lever itself is arranged by means of the sleeve freewheel on the prolonged side of the spur gear shaft.
In order to provide a modular design of the electromechanical driving device, the closing device is arranged on the transmission housing itself. The electromechanical driving device therefore forms the drive both for the windshield wiping device and for the actuation of the locking means of the tailgate and/or of the tailgate windshield, in which case all the components can be embodied as a premountable unit. Said unit has to be integrated in a modular fashion for mounting in the tailgate.
Further measures which improve the invention are illustrated in more detail below together with the description of a preferred exemplary embodiment of the invention on the basis of the figures.